A union claims the prison service has sacked officers ahead of new laws on disability discrimination.

The Prison Officers Association says there has been an increase in dismissals on medical grounds before legislation comes into effect.

The Home Office has denied the charge, saying it has been addressing sickness absence for a number of years.

The Disability Discrimination Act will cover the police, fire and prison services from 1 October.

Duncan Keys, the POA's assistant secretary, said there was a "complete lack of understanding", on the part of the Prison Service of its new obligations under the legislation.

"We believe that [the increase in dismissals] is because of the imminent introduction of the Disability Discrimination Act," he said.

"There's a sort of inbred understanding that the Prison Service simply doesn't employ people with disabilities."

But the Home Office, responsible for the Prison Service, said there had been no policy change.

The POA says more work is needed to accommodate disabled staff

"The Prison Service will only dismiss any member of staff after extensive consideration of the case, and only after exhausting any options for retaining or deploying staff," said a spokesperson.

The prison service was trying to "create a working environment where staff are confident that they can disclose their disability without fear of discriminatory repercussions," said the spokesman, stressing that there was a five-year action plan within the organisation.

"Diversity training, which covers disability, is being given to all staff in a rollout programme," he said.

As with the other two uniformed services, high levels of physical fitness continue to be an entry requirement for prison officers.

"It is essential that prison officers possess a standard of physical fitness that enables them to perform physically demanding tasks professionally, and without risk of injury to either themselves or others."

'Culture of intolerance'

But according to the POA, this culture led to intolerance towards staff who develop or declare impairments.

I passed the exam, but one of my colleagues later commented that I'd sat the 'thickos' exam

Prison officer with dyslexia

"I think a lot of our members are hiding impairments because they fear that telling the truth will lead to dismissal," said Mr Keys.

Although the Home Office has been working on policies to promote 'disability confidence', the POA said the system was now less flexible now that it was some years ago.

"There was a breed of enlightened governor who would stay in post for several years and who would try to keep officers employed because they valued the individual's experience and dedication," said Mr Keys.

"Now people move through the system really quickly and are less likely to bend the rules."

Lack of understanding

One prison officer, speaking on condition of anonymity, told the BBC his dyslexia had been used to prevent his promotion within the service over the last 10 years.

When he applied to sit promotion exams, he was told to do them at a different prison to the rest of his colleagues, he said.

"I passed the exam, but one of my colleagues later commented that I'd sat the 'thickos' exam', which was quite hurtful," he said.

The officer said he was denied extra reading time, something many people with dyslexia require because of how they absorb information, when preparing for a role-play exercise in a promotion test.

He told the BBC he doubted the service would be ready for its legal obligations.

"No chance - they'll run around like headless chickens," he said.

The POA has produced a booklet in conjunction with the Disability Rights Commission to raise awareness among its members.

"We accept that these changes can't all happen overnight," said Duncan Keys of the union.

"We'd like to help the Prison Service to improve people's confidence - so far they're not asking for that help."